This invention relates to fluid pumping apparatus and, more particularly, to a submersible pump that may be used to separate and recover an underground layer of floating fluid, including hydrocarbons.
It is often desirable, and sometimes required, to decontaminate groundwater by pumping contaminants from a well. This is possible if the contaminant is a separate or floating layer on or within the groundwater. If the contaminant is a hydrocarbon, an added benefit is that the fluid may be recycled for reuse. Pumps used to remove a floating liquid layer to an elevated location are disclosed in U.S. Pat. Nos. 6,220,823; 5,147,184; 3,669,275; 4,243,529; 4,273,650; 4,663,037; 4,872,994; and 4,998,585.
A problem with existing designs is that they often require numerous component parts, including moving parts, and therefore tend to be complex. Such products often use stationary inlets in conjunction with hydrophobic screens, floating inlets attached to coils, or more complex inlet structures used in conjunction with sensors and pneumatic cylinders. Stationary inlets may be mispositioned out of the product when the water level drops, or they can be completely submerged under the water if the level raises to an unacceptably high degree Hydrophobic screens can be easily fouled and plugged, and floating inlets can hang up for various reasons. Coils may also be plugged by discharged hydrocarbons, such as spent motor oil and other thicker fluids.
In my U.S. Pat. No. 6,220,823, I describe an air-operated, submersible pump having a simplified inlet design, resulting in an economical and reliable apparatus that many be used for water pumping of fluid separation, including the recovery of viscous hydrocarbon products. The pump includes a pump body having a length, a wall, an air inlet, and a discharge port. The inlet area fluidly penetrates through a portion of the wall, and a flexible seal, disposed within the pump body, is supported in overlying registration with the fluid inlet. A pressure-operated valve in fluid communication with the discharge port facilitates a refill mode of operation, wherein fluid surrounding the pump flows into the pump body through the inlet area; and a discharge mode of operation wherein the air inlet is pressurized, causing the seal to seat against and seal off the inlet area, and fluid which flowed into the pump body to be discharged through the discharge port. The inlet area preferably comprises a plurality of apertures formed through the wall of the pump body arranged as one or more linear arrays lengthwise along the pump. The apertures may include a raised rim where they protrude into the pump body thereby helping the seal to seat thereagainst. Alternatively, the inlet area may incorporate slots, a mesh or screen panel, or a porous member, including a hydrophobic screen.
When deployed to separate and recover a layer of fluid floating on water, a pump according to the invention pump further includes a water outlet and a water-outlet seal. During the refill mode of operation, water including the floating layer of fluid flows into the pump body through the inlet area, and in the discharge mode of operation, the pressurization further causes water which flowed into the pump body to be discharged through the water outlet until the outlet is sealed, after which the fluid which flowed into the pump body is discharged through the discharge port. In implementing this design, I have found that relatively high pressure, on the order of 40 p.s.i., is required to satisfactorily seal the flap to the inlet region. At lower pressures, of 30 p.s.i. and less, for example, the integrity of the seal could be compromised, causing back flow and potential turbulence, potentially upsetting the product/water interface.
This invention resides in an improved, air-operated, submersible pump having a bladder-controlled inlet design resulting in an economical and reliable apparatus that may be used for water pumping of fluid separation, including the recovery of viscous hydrocarbon products.
The pump includes a pump body having a length, a wall with a fluid inlet area, exhaust line, an air inlet, discharge port and a bladder air-supply line. The inlet area fluidly penetrates through a portion of the wall, and an air-operated bladder, disposed within the pump body, is supported in overlying registration with the fluid inlet. A set of pressure-operated valves facilitate a refill mode of operation, wherein fluid surrounding the pump flows into the pump body through the inlet area, and a discharge mode of operation wherein the bladder is pressurized to seat against and seal off the bladder inlet area, following fluid which flowed into the pump body to be discharged through the discharge port.
In the preferred embodiment, the inlet area comprises a plurality of apertures formed through the wall of the pump body arranged as one or more linear arrays lengthwise along the pump. The apertures may include a raised rim where they protrude into the pump body thereby helping the bladder to seat thereagainst. Alternatively, the inlet area may incorporate slots, a mesh or screen panel, or a porous member, including a hydrophobic screen.
When deployed to separate and recover a layer of fluid floating on water, a pump according to the invention pump further includes a water outlet and a water-outlet seal. The water-outlet seal preferably comprises a check ball seat, and a density-less-than-water check ball which engages with the seat in the presence of fluid from the floating layer.
The separate bladder air-supply line and air-supply/exhaust lines include pressure-operated valves that sequence in alternating fashion as the pump cycles between refill and discharge states. During refill, a low flow is permitted out of the bladder air-supply line, so that the bladder can move away from the fluid inlet area. An exhaust valve in the air-supply/exhaust line allows the volume of the pump body to be discharged rapidly, enabling a quick refill of fluid into the pump body. To discharge, a high flow into the bladder air-supply line inflates the bladder, causing it to seal off the fluid inlet area, while a relatively low flow enters into the air-supply/exhaust line, to push the water out the water-outlet until it seals off, after which time the fluid of interest is pumped out the discharge line, and the cycle repeats.
The valve configuration, which may be located above-ground or on the pump body, permits a conventional above-ground controller to be used to operate the pump. During the refill mode of operation, water including the floating layer of fluid flows into the pump body through the inlet area, and in the discharge mode of operation, the pressurization further causes water which flowed into the pump body to be discharged through the water outlet until the outlet is sealed, after which the fluid which flowed into the pump body is discharged through the discharge port.